problems with co-ownership

[N/A N/A]

I have a sister who is married and lives in Canada; I live in a townhouse that my mom owned and she lived with me. My mom passed away last month leaving me and my sister as co-owners of the townhouse. Although my mom's will stated that all her assets be sold upon her death (including the TH), it did not have to happen immediately; no one was throwing me out on the street just to sell the property. Besides, we have been remodeling for the past 2 years and only have the loft and a bathroom left which we want to complete before putting it on the market. Logically, we should each pay half the mortgage ($1050/mo), utilities, etc and then split the profit after the TH is sold. However, my sister does not have the money to do this. Moreover, she and her husband both fervently believe that even if I pay half the mortgage, I should also be paying rent (amount to be determined) since I am living in the TH. No one has been able to explain who gets this "extra" rent money but they both say it is necessary since no one can rent a place like this for $500/mo. Frankly, I think I should be paid a management fee for living in and caring for the place. I have tried to explain that we get equity in the house as the mortgage gets paid and we both benefit when the house is sold; also, my sister comes into town and stays here for rather lengthy visits whenever she wants so its not like she's not benefiting from her investment, too. She is also against paying half because she claims she pays rent in Canada...which is not quite true as her husband is the only one who works so she doesn't contribute one dime to her rent there. My sister claims she's not trying to make any money off me but I find that hard to believe. I say she is clueless as to how mortgages work versus paying rent. Am I missing something here? Can someone suggest what would be fair to both parties? Thanks for any help you can provide.